Offshore Special Area of Conservation: Darwin Mounds SAC Selection Assessment © Brian Bett, NOC (1999)∗ Version 4.0 (1st July 2008) ∗ Cover photo illustrates cold water coral ‘thicket’ on the Darwin Mounds Introduction This document provides detailed information about the Darwin Mounds site and evaluates its interest features according to the Habitats Directive selection criteria and guiding principles. The advice contained within this document is produced to fulfil requirements of JNCC under Part 2 of the Offshore Marine Conservation (Natural Habitats, & c.) Regulations 2007, relating to the conservation of natural habitat types and habitats of species through identification of Special Areas of Conservation (SACs) in UK offshore waters. Under these Regulations, JNCC has an obligation to provide certain advice to Defra to enable the Secretary of State to fulfil his obligations under the Regulations, and to Competent Authorities to enable them to fulfil their obligations under the Regulations. This document includes information required under Regulation 7 of the Offshore Marine Conservation (Natural Habitats, & c.) Regulations 2007 to enable the Secretary of State to transmit to the European Commission the list of sites eligible for designation as Special Areas of Conservation (SACs). JNCC have been asked by Defra to provide this information to Government. Sites eligible for designation as offshore marine SACs are selected on the basis of the criteria set out in Annex III (Stage 1) to the Habitats Directive and relevant scientific information. Sites are considered only if they host a Habitats Directive Annex I habitat or Annex II species. Moreover, sites for Annex II species must contain a clearly identifiable area representing physical and biological factors essential to these species’ life and reproduction to be eligible. Socio-economic factors are not taken into account in the identification of sites to be proposed to the European Commission1. In addition to information on the Annex I habitats and/or Annex II species hosted within the site, this document contains i) a chart of the site, ii) its name, location and extent, and iii) the data resulting from application of the criteria specified in Annex III (Stage 1) to the Habitats Directive. This is in line with legal requirements outlined under Regulation 7. JNCC has adhered to the format established by the Commission for providing site information. This format is set out in the ‘Natura 2000 Standard data form’ (CEC, 1995) (prepared by the European Topic Centre for Biodiversity and Nature Conservation on behalf of the European Commission to collect standardised information on SACs throughout Europe). 1 Following European Court of Justice ‘First Corporate Shipping’ judgement C-371/98 (7 November 2000) Darwin Mounds SAC Selection Assessment: Version 4.0 Page 2 of 14 01/07/08 Document version control Version and issue date Amendments made Issued to and date DarwinMounds_SelectionAssessment_4.0. - New site map inserted (boundary Secretary of State (July doc (1st July 2008) unchanged) 2008) DarwinMounds_SelectionAssessment_3.1. - Draft SAC changed to possible SAC Public consultation doc (13th November 2007) (December 2007) DarwinMounds_SelectionAssessment_3.0. - New introductory text, revised site JNCC Committee (June doc (25th May 2007) summary (refers to corrected boundary of 07) and UK Marine Rockall Trough and Bank Regional Sea) Biodiversity Policy and map layout, heading & text Steering Group amendments (September 07) - Revised site boundary and area - Additional guiding principles for site selection incorporated under Global Assessment - Conservation Objectives and Advice on Operations moved to separate document DarwinMoundsDossier_2.0_draft.doc (26th - Draft Conservation Objectives and Defra, Devolved August 2006) (revised) Advice on Operations added. Administrations, and - Map layout revised other Govt. departments (25th September 2006) Darwin Mounds proposed Special Area of JNCC Committee (June Conservation: JNCC 02 P10 (June 2002) 2002) and Defra (2002) Further information This document is available as a pdf file on JNCC’s website for download if required (www.jncc.gov.uk) Please return comments or queries to: Charlotte Johnston Joint Nature Conservation Committee Monkstone House Peterborough Cambs PE1 1JY Email: [email protected] Tel: +44 (0)1733 866905 Fax: +44 (0)1733 555948 Website: www.jncc.gov.uk Darwin Mounds SAC Selection Assessment: Version 4.0 Page 3 of 14 01/07/08 Darwin Mounds: SAC Selection Assessment 1. Site name 2. Site centre location Darwin Mounds 59º45'30″, -7º-13'0″ (Datum: WGS 1984) 3. Site surface area 4. Biogeographic region 137,726 ha/1,377 km2 Atlantic (Datum: WGS 1984 UTM Zone 29 North, calculated in ArcGIS) 5. Interest feature(s) under the EU Habitats Directive 1170 Reefs Darwin Mounds SAC Selection Assessment: Version 4.0 Page 4 of 14 01/07/08 6. Map of site Darwin Mounds SAC Selection Assessment: Version 4.0 Page 5 of 14 01/07/08 7. Site summary The Darwin Mounds is an extensive area of sandy mounds formed by seabed fluid expulsion, each of which is capped with multiple thickets of Lophelia pertusa, a cold- water coral. These thickets qualify as Annex I Reef according to the European Commission interpretation (CEC, 2007). The number of thickets vary per mound and may be between one and several metres wide and high. Hundreds of mounds lie within the site but two particularly dense fields of mounds are present to the north east and north west limit of the area (Bett, 2001). Each of the mounds is approximately 100m in diameter and 5m high, and distinguished by a 'tail' feature visible on sidescan sonar. The mounds support significant populations of the xenophyophore Syringammina fragilissima (a 15 cm diameter single celled organism) that is widespread in deep waters, but occurs in particularly high densities on the mounds and the tails (Bett, 2001).The occurrence of Lophelia pertusa reef as thickets capping sandy mounds is believed to be unique due to the particular geological processes which formed the mounds and the fact that the coral is growing on sand rather than a hard substratum (Masson et al, 2003). The individual reefs on each mound provide a habitat for various species of larger invertebrates such as sponges and brisingiid starfish. The Darwin Mounds lie at the north end of the Rockall Trough at a depth of approximately 1000m. They are beyond the shelf break, approximately 160 km north west of Cape Wrath, Scotland. This site occurs largely within the Rockall Trough and Bank Regional Sea, although a small part of the site extends into the Scottish Continental Shelf Regional Sea (JNCC, 2004a; Defra 2004). There are no other SACs within the Rockall Trough and Bank Regional Sea. However, the Wyville Thomson Ridge site, which lies close to the Regional Sea boundary, has been recommended to Defra for its reef features. This site is shown below with its characteristic features. Possible Notable characteristics of the Reef interest feature (Southampton SAC Oceanography Centre, 2000) Wyville Wyville Thomson Ridge comprises stony reef (iceberg ploughmarks) Thomson and bedrock reef, and is located in a transition area between three Ridge biogeographic regions. The reef habitats on the Ridge are unique due to the distinctive hydrographic regime. The faunal communities are composed of species representative of hard marine substrata in deep water such as sponges, brachiopods, octocorals, carpet forming featherstars and sedentary, filter-feeding holothurians. The Wyville Thomson Ridge reefs differ substantially from those of the Darwin Mounds: they consist of iceberg ploughmarks and bedrock reef, and support different ecological communities due to both the hydrographic regime and substratum. Although hard corals are found at both sites, their growth as reefs on sandy mounds at the Darwin Mounds site differentiates the two sites. 8. Site boundary The proposed boundary for the Darwin Mounds site has been defined using JNCC’s boundary definition guidelines. These were agreed by the Joint Nature Conservation Committee and modified subsequent to public consultation in 2003 (JNCC, 2004b). The proposed boundary is a simple polygon defined by whole degrees and minutes, fully Darwin Mounds SAC Selection Assessment: Version 4.0 Page 6 of 14 01/07/08 enclosing the minimum area necessary to ensure protection. As bottom trawling is a significant threat to the interest feature the proposed boundary includes a margin to ensure its protection. The maximum depth of water around the feature is 1000-1100 m. Fishing vessels which are bottom trawling in the region need a minimum towline length of twice the depth of water in which they are fishing (SERAD, 2001). Therefore, assuming a ratio of 2:1 fishing warp length to depth, the proposed boundary is defined to include a margin of 2200 m from the Lophelia pertusa reefs. The location of the Annex I habitat is drawn from data provided courtesy of Southampton Oceanography Centre (Bett, 1999; Bett et al., 2001). Note that the boundary now proposed (2007) for the SAC has been aligned with the area permanently closed to bottom trawling through the EU’s Common Fisheries Policy in 2004 (Reg 602/2004). This area now excludes the NW and NE corners of the simple box boundary proposed in 2002, following the above guidance on site boundary definition. There was no evidence for the presence of mounds or coral reef in these two corners of the initial boundary box. 9. Assessment of interest feature(s) against selection criteria 9.1 Reefs Annex III selection criteria (Stage 1A): a) Representativity The Darwin Mounds site is located in the Rockall Trough and Bank Regional Sea, and represents biogenic reef formed by Lophelia pertusa on sandy substratum in a deep waters. The energy levels at this site are moderate, and the reef is subject to minimal coastal influence. The Darwin Mounds are considered to be an unusual example of cold coral reefs in UK waters due to the growth of Lophelia reefs on sandy mounds. The faunal communities are representative of those present on Lophelia reefs, and consist largely of sessile or hemi-sessile invertebrates such as sponges and brisingiid starfish.